An effective oral composition can maintain and preserve tooth appearance by removing dental stains and polishing the teeth. It may clean and remove external debris as well, which can aid the prevention of tooth decay and promote gingival health.
Abrasives in oral compositions aid in the removal of the tightly adherent pellicle film to which dental stains affix. Pellicle film usually comprises a thin acellular, glycoprotein-mucoprotein coating, which adheres to the enamel within minutes after teeth are cleaned. The presence of various food pigments lodged within the film accounts for most instances of teeth discoloration. An abrasive may remove the pellicle film with minimal abrasive damage to oral tissue, such as the dentin and enamel.
In addition to cleaning, it may be desirable for abrasive systems to provide polishing of tooth surfaces, as polished surfaces may be more resistant to ectopic deposition of undesirable components. Tooth appearance may be improved by imparting a polished character to the teeth, because the surface roughness, that is, its polish, affects light reflectance and scattering, which integrally relate to the teeth's visual appearance. The surface roughness also affects tooth feel. For example, polished teeth have a clean, smooth, and slick feel.
Numerous dentifrice compositions use precipitated silicas as abrasives. Precipitated silicas are noted and described in U.S. Pat. No. 4,340,583, Jul. 20, 1982, to Wason, EP Patent 535,943A1, Apr. 7, 1993, to McKeown et al., PCT Application WO 92/02454, Feb. 20, 1992 to McKeown et al., U.S. Pat. No. 5,603,920, Feb. 18, 1997, and U.S. Pat. No. 5,716,601, Feb. 10, 1998, both to Rice, and U.S. Pat. No. 6,740,311, May 25, 2004 to White et al.
A need exists for an abrasive system that has good compatibility with oral care actives and key dentifrice components, while providing effective and safe cleaning and polishing of dental tissue. In addition, there exists a continuing need for abrasives that can produce superior cleaning and polishing at reduced costs. The fused silicas of the present invention may provide one or more of these advantages. Fused silicas wherein the particles are spherical may particularly provide these advantages. Therefore, the present invention relates to oral care compositions comprising fused silica, wherein at least 25% of the fused silica particles are spherical.